The present exemplary embodiment relates generally to power management. It finds particular application in conjunction with a multi-device print system comprising a plurality of print devices and will be described with particular reference thereto. However, it is to be understood that it also finds application in other usage scenarios and is not necessarily limited to the aforementioned application.
Print devices typically include different operating modes corresponding to different power consumption levels. Such operating modes typically include idle modes and power saving modes. In an idle mode, a print device is ready to be used for printing, which typically requires the most power. When not in use, the print device is cycled down to a power saving mode, also known as standby mode, low power mode, or sleep mode. In the power saving mode, the print device draws enough power to support certain functions of the print device, but requires a warm up period before it is fully operational again.
The warm up period for a print device is actuated, for example, when a print job is received for printing or a user actuates the print device. The print device control system then activates components that draw additional power in preparation for use of the print device. For example, a printer may heat a fuser roll and cause the marking material to be readied for use. In the case of laser printers, this generally involves circulating the toner particles in a developer housing. For solid ink printers, the solid inks are heated to above their melting points.
Once a print device has been used, it may remain in an idle mode at the higher power consumption level for some predetermined period of time (a time-out), to maintain one or more components within an operational temperature range or state. The time-out reduces the number of cycles experienced by the components, which helps preserve their operational life and also reduces or eliminates waiting time for the customer. If the print device is not in use again by the preset time-out, the print device begins to cycle down to the power saving mode.
Currently, in most print devices, the inactivity period to wait before entering into sleep mode is either set by the administrator or predefined by the print device manufacturer according to environmental standards, such as Energy Star. Until 2006, print devices were evaluated as Energy Star compliant based on whether the manufacturer respected the time-out recommendations of the Environmental Protection Agency (EPA). The recommendations were dependent on the type of print device (e.g., scanner, copiers, multi-function devices) and its speed capabilities. Further, the recommendations were arbitrary and not self-adapted by any logic or intelligence embedded on print devices.
Today, Energy Star criteria are based on the evaluation of power consumption during a fixed period of a week in which the print device receives requests with a predefined standard usage pattern. The result of the evaluation method is the Typical Energy Consumption (TEC) value measured in kWh and which must be under a certain level in order to obtain the Energy Star certification. For example, for a color multi-function device producing 24 images per minute (IPM), its power consumption must be below (0.2 kWh*24)+5 kWh. Although the current evaluation method takes into account a usage pattern, it does not take into account the stochastic nature of usage patterns.
In order to respect TEC maximum levels, manufacturers employ time-out strategies which reduce the time-outs and make improvements in power consumption. One strategy for accomplishing this is to adjust time-out according to the unavailability time of the print device during switching from sleep to an active status. Another strategy is to set time-out according to the relation between the idle period and the wakeup delay (i.e., the time to get out of power saving mode). If this relation is small, time-out increases; otherwise, time-out decreases. However, in most cases, time-out values are static and/or not adapted to the real usage of devices.
Further, print devices are typically deployed in a multi-device print system comprising a plurality of print devices, where each print device is typically capable of executing incoming print jobs. In such systems, users typically specify the print devices they want to execute their print jobs. In doing so, users commonly select the print devices that are most convenient or best for them. However, users often fail to consider the power costs. For example, while a user may prefer a certain print device, if the print device is in a power saving mode, the cost of waking the print device up may outweigh the “cost” to the user of printing to another print device.
The present disclosure provides a new and improved system and method which overcome the above-referenced problems and others.